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  • Writer's pictureBarry Michael Aldridge

Unlocking innovation to enhance train fleet performance.

Updated: Oct 25, 2023

Through collaborative rail stakeholder research and development, SME Flotec identified issues with DMU train fleets which were having adverse effects on their performance and reliability.

This in turn was resulting in critical down time, causing disruption to the UK rail network and substantial inconvenience for the passengers who rely on it.

Upon deeper investigation, Flotec noticed that a modification to the fan and cooling system would deliver significant improvements to fleet performance.

The problem.

DMU trains can experience substantial engine issues due to a build-up of contaminants and debris in their systems. The result is a ‘return to idle’ (RTI) scenario which can catastrophically slow the train down or even worse, render it completely immobile.

The complication is two-fold where delays or cancellations disrupt the rail service which delivers a negative customer experience. Secondly, an inefficient engine has a detrimental impact on the environment.

The solution.

Flotec designed, engineered, and tested an innovative variable pitch fan and engine temperature management system which was substantially more effective in keeping a DMU engine appropriately cool and filtered, helping to eliminate RTI engine failure.

This product and system development is unique to the UK rail market.

How does the variable pitch fan work?

Traditional fans are rotationally fixed, meaning, they are limited to only drawing air ‘in’ through the radiators.

Due to the one rotational direction, traditional fans pull contaminants into the radiator fins which escalates RTI probability.

The subsequent radiator blockage very quickly effects air flow, making the radiator inefficient.

This forces the system to work harder to maintain the cooling temperature.

Ultimately, the thermostatic control engages, shutting the engine down.

The blades of Flotec’s variable pitch fan are unique because they rotate on their own axis to change the pitch and reverse through the cross position.

This guarantees the air will always be in the optimum position to produce maximum flow when in both cooling and cleaning modes.

Additionally, fitting a VPF effectively maintains radiator cooling efficiency by eradicating blocking contaminants, which enhances energy savings, and further helps to eliminate RTI instances.

Furthermore, a hard-wired fan control system installed into the existing electronics of the train ensures that the cleaning process is not engaged when the vehicle is either stationary or drawing into a station.

During the development of the variable pitch fan, Flotec realised that the use of a traditional fan system meant that train fleet maintenance personnel had to conduct frequent high-pressure washes to the engine radiators to remove an excessive build-up of debris and contaminants.

This also resulted in extra wear and tear to the radiator fins, thus, reducing engine temperature control.

Installing a variable pitch fan reduces the frequency of washing which in turn, lessens damage to the radiators.

Maintenance costs are lowered, and the lifespan of the radiator fins extended with improved performance.

How is the Flotec variable pitch fan solution implemented?

The Flotec engineering team can attend site and inspect train fleets and advise of the most appropriate solution and complete the required modification and system upgrade.

In addition to the variable pitch fan, Flotec offers a series of engineering solutions, consisting of:

• Hydrostatic Hose Applications

• Reservoir Maintenance

• Advanced Fan Control

• Variable Displacement Pump (VDP) Integration

Hydrostatic hose

It is well known that the poor routing of hoses can lead to premature failure.

Hoses are often installed at too long a length making them weighty and hang low to the ground where damage from ballast and debris often occurs.

Hose degradation can become a major issue.

Flotec installs superior EN 45545-2 fire safe hydrostatic hoses and correctly routes them with sophisticated clamping to overcome the issue of damage and frequent failure.

This guarantees a fault free life cycle between scheduled overhauls.

Hydrostatic reservoir overhaul

Cleaning reservoirs is often overlooked where Flotec has witnessed some DMU reservoirs not being maintained for up to twenty years.

Neglecting the reservoirs can lead to a build-up of debris resulting in component contamination and failure.

Flotec can either overhaul or replace the reservoirs to ensure optimum efficiency.

Electronic fan control vs. valve thermostatic fan control

Original electronic fan controls proved unreliable and were replaced with valve thermostatic controls, where this became the norm.

However, these in themselves have created issues, through worn mechanical parts where they then fail to work to the correct cut in temperature.

This issue fails to trigger full fan speed at the precise time it is required, resulting in RTI.

These valve controls have become increasingly obsolete as well as costly to maintain.

With recent advancements in electronic fan control technology, Flotec recommends this as a more reliable integration.

Upgrade to variable displacement pumps (VDPs)

Whilst fixed displacement pumps (FDPs) have been used on rolling stock for many years (forming part of the original OEM design), Flotec has noticed some significant drawbacks.

Firstly, the pump output is dependent on engine speed.

This is not too much of a problem if the gearbox change points are correct and the gearbox reverts to torque converter mode at circa 60 mph.

However, if the point of change is below this the engine will lug down on an incline, resulting in lower fan speeds when higher coolant load is required.

Another issue with FDPs is that if the engine is running slow, the fan will also run slow and at a time it is required to perform.

Installing a variable displacement pump (VDP) ensures that when cooling is not required, the pump automatically shuts down and only pumps oil around the system where necessary.

This is successful in reducing unnecessary heat generation and less wear and tear of other components.

The result is optimum engine performance coupled with additional fuel savings.

A variable displacement pump is not controlled by engine speed and alters to suit whatever cooling is required at any given time.

The benefits:

The cooling solution has returned results of 750,000 miles of use giving it an average percentage increase of 60% over other product alternatives currently being used on the UK rail network.

Flotec believes the variable pitch fan and supporting system upgrade contributes towards the following three points:

1. Planet Saving

2. Disruption Depleting

3. Customer Pleasing

Planet saving:

Whilst great moves are being made in alternative power solutions to achieve net zero, the phase out of diesel will not be an overnight affair. With either DMU or bi-mode trains still very much in operation, the variable pitch fan is critical in making these fleets run more efficiently which in turn has improved environmental benefits due to a better performing engine.

Whilst the phase out is taking place, it seems wise to make existing diesel fleets as environmentally friendly as possible.

Disruption depleting:

Helping to eliminate engine failure and RTI issues means that the Flotec variable pitch fan innovation will be a critical success factor in reducing service disruption and delay to the network thus, improving customer experience.

Customer pleasing:

The variable pitch fan and wider system upgrade makes train fleets more reliable, efficient, and robust which in turn helps to reduce delays and even cancellations caused by existing RTI engine complications.

Customers expect reliability and availability and Flotec’s solution can support TOCs in consistently providing the proposition and service that customers demand.

Equally important is the freight operators who can all benefit from this technology, ensuring products and goods arrive at their destination in a timely manner.

In 2021, the Flotec variable pitch fan won an award for innovation in manufacturing and engineering through the Reach PLC East Midlands Innovation Awards.

Judges were impressed with Flotec’s preventative approach – as opposed to a reactive one – because the variable pitch fan and associated system technology pre-empts delays and works to eliminate them before they occur, benefitting the rail network and those who rely on it.

Importantly, the variable pitch fan and accompanying system is currently in use throughout the UK rail network where it is tried, tested, and trusted by several major TOCs.

Flotec is proud to be an official innovation partner with Angel Trains.

How flexible is this solution?

Flotec's offering is fully flexible and can be tailored to individual operators’ requirements and is installed by a fully trained, experienced, and diverse engineering team who are well versed in working collaboratively with train companies throughout the UK.

Flotec offers rail clients a mix of different methods to help get their rolling stock up to speed!

The four levels of modification will suit different fleet operators, for their varying requirements such as geographic location or ecological environments.

As an example, certain fleets may encounter steep incline ‘climb power’ issues due to an exceptionally hilly terrain whilst others will face problems such as contaminant blockage and some will be exposed to all contributing elements.

Flotec can advise on the most appropriate option on a one-to-one basis.

A breakdown of the available options is listed below:

Option 1

Leave the system as standard, renew the hoses, service the reservoir, check system pressure and performance check.

Option 2

Modify the system. Hose improvement, reservoir service, remove the thermo valve and pipework, fit electronic fan control valve, in place of thermo valve.

Option 3

  • Renew any hoses and service the reservoirs

  • Replace the fixed displacement fan pump with a variable displacement fan pump

  • Replace the Thermo valve with a thermistor

  • Fit a programmable CED controller, to electronically control the fan speed in relation to the engine coolant temperature, by varying the displacement of the new fan pump. In the event of an electrical failure the fan will revert to full speed

Option 4

The same as option 3 but also adding a variable pitch fan. This will help keep the radiator cool, clean, and efficient so to eliminate RTI.

Flotec’s variable pitch fan and supporting features can be installed at OEM new build stage or as part of an overhaul process for existing train fleets.

If you have a DMU or bi-mode train in operation, then Flotec can help make your rolling stock more environmentally friendly, efficient, and cost beneficial.

For more information, contact the team on 01509 230 100 or email:

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